In my non-expert opinion, and based on a description of that knife I read and the law quoted by Glistam, that knife really does sound like it technically qualifies as a "switchblade", and is therefore illegal for you to carry.
As someone who has been through the criminal justice system, I would strongly suggest that you carry a different knife and enjoy the S&W at home. While it's true that you may never get caught carrying that knife, it's not worth taking the gamble. You never know how or when the cops will have the opportunity to "catch" you. I met a lot of guys behind bars who never thought they would get caught doing what they were doing. And once you get caught, there are no "do overs". If you get caught and if you are lucky, a cop may simply confiscate the knife and let you go. If you are not lucky, well, imagine having to call your parents from jail, imagine them having to miss work to attend your various court hearings, and imagine how happy they would be to have to pay hundreds, or thousands of dollars in fines and court costs. And then of course there is the unpleasantness of probation and community service and having a criminal record (weapons offense), etc, etc.
I advise you to take the law and the criminal justice system very seriously (I'm not saying you don't already. I'm just giving that advice). The criminal justice system is no joke. Don't expect mercy or understanding from cops or prosecuters or judges just because you're a "kid" or because you're not a "criminal". Many people undersestimate the criminal justice system because they have no experience with it. But if you ever get arrested and charged with a crime, you'll realize, like many often learn too late, that it is very real, and very serious, and that it can really screw-up your life.
Like I said, don't take the gamble. Carry a different knife.